This invention relates to a speed detecting device for a marine propulsion unit and more particularly to an improved arrangement for transmitting a water pressure signal from a marine propulsion unit to a remotely positioned indicator.
A popular form of speed indicator for watercraft employs a system in which a water pressure signal is transmitted from the lower unit of the outboard drive to a remotely positioned transducer and indicator that gives a speed signal indication. The water pressure signal is derived from a forwardly facing inlet opening that is formed in the lower unit at a place below the normal water level. It is necessary, of course, to transmit this signal through the outboard drive unit and to the remotely positioned indicator. This is normally done by means of a conduit that is formed in the lower unit and which communicates with a flexible conduit that extends from the outboard drive unit to the remotely positioned indicator. Although these systems are quite advantageous, there are some disadvantages in the construction and operation of the prior art systems for transmitting the signal from the pressure sensing inlet to the remotely positioned indicator.
In one form of prior art construction, the conduitry is comprised of first and second conduits that are formed in the housings of the lower unit and upper unit of the marine outboard drive and which conduits communicate with each other when the housings are connected. However, with this form of construction it has been the practice to employ a flexible conduit that must be connected externally to the upper unit housing in communication with its conduit for conveying the water pressure signal to the remotely positioned indicator. This type of construction leaves the flexible conduit exposed where it might be damaged, provides a somewhat unsightly appearance and also requires some care in final assembly to make sure that the flexible conduit does not become damaged or kinked on final assembly.
Another form of construction employs a conduit that is formed in the lower unit housing with the flexible conduit being affixed directly to the lower unit housing and extending in part through the upper unit housing and then to the remote location. Although this type of construction has a neater appearance, it also requires a connection to be made through the outside of the upper unit housing so as to facilitate assembly and disassembly since the flexible conduit is normally formed from two interconnected portions that must be interconnected through the upper unit housing.
It is, therefore, a principal object of this invention to provide an improved conduit arrangement for transmitting a water pressure signal from a marine outboard drive to a remotely positioned indicator.
It is a further object of the invention to provide a conduit assembly of this type which minimizes the number of connections with must be made after the housing assemblies are connected to each other and which also conceals a major portion of the flexible conduit so as to avoid damage and improve neatness.
It is a further object of this invention to provide an improved, simplified and effective construction for transmitting a water pressure signal to a remotely positioned indicator from a marine outboard drive.